A wireless communication device, such as a mobile phone device or a smart phone, may include two or more Subscriber Identity Modules (SIMs). Each SIM may correspond to at least one subscription via one or more Radio Access Technologies (RATs). Such a wireless communication device may be a multi-SIM wireless communication device. In a Multi-SIM-Multi-Active (MSMA) wireless communication device, all SIMs may be active at the same time. In a Multi-SIM-Multi-Standby (MSMS) wireless communication device, if any one SIM is active, then the rest of the SIM(s) may be in a standby mode. The RATs may include, but are not limited to, Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA) (particularly, Evolution-Data Optimized (EVDO)), Universal Mobile Telecommunications Systems (UMTS) (particularly, Time Division Synchronous CDMA (TD-SCDMA or TDS) Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), High-Speed Downlink Packet Access (HSDPA), and the like), Global System for Mobile Communications (GSM), Code Division Multiple Access 1× Radio Transmission Technology (1×), General Packet Radio Service (GPRS), Wi-Fi, Personal Communications Service (PCS), and other protocols that may be used in a wireless communications network or a data communications network.
A MSMS (e.g., a Dual-SIM-Dual-Standby (DSDS)) wireless communication device may have multiple subscriptions. In some cases, a first subscription may be utilized for Internet Protocol (IP) Multimedia Subsystem (IMS), providing services such as Voice-Over-LTE (VoLTE), Short Messaging Service (SMS), or Rich Communication Service (RCS). A second subscription may be a Designated Data Subscription (DDS) for data services. In this configuration, once an IMS activity (e.g., a VoLTE call, SMS, RCS) has completed at the IMS subscription, the wireless communication device may immediately release the connection (e.g., Radio Resource Control (RRC) connection) of the IMS subscription, rather than wait for the network to release the connection after detecting data inactivity of the wireless communication device (after 10 or 20 seconds based on data inactivity timer configured at the network). Occasionally, when the connection is just released, the IMS subscription may need to establish a connection again within few seconds for a scheduled IMS signaling, such as periodic IMS Registration/Subscribe/Publish request scheduled to be transmitted periodically. Substantial resources of the wireless communication device and the network may be consumed for reestablishing the connection and resuming the Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs). At the same time, the DDS subscription loses the radio frequency (RF) resource of the wireless communication device, which is locked by the IMS subscription.